This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2003-162632, filed Jun. 6, 2003, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an improvement in a deflecting yoke apparatus used in a cathode ray tube of, e.g., a color television receiver or a color display apparatus. Further, the present invention relates to a television receiver using the above-described deflecting yoke apparatus.
2. Description of the Related Art
As is well known, the above-described deflecting yoke apparatus controls in such a manner that respective electron beams R (Red), G (Green) and B (Blue) corresponding to three primary colors emitted from an electron gun scan along a fixed path on a fluorescent screen by applying deflection in a horizontal direction and a vertical direction to the respective electron beams R, G and B.
This deflecting yoke apparatus comprises a separator formed in a substantially conical shape, and generates to a horizontal deflecting coil provided on the inner side of the separator and a vertical deflecting coil provided on the outer side of the same a magnetic field by passing serriform deflecting currents synchronized with horizontal and vertical cycles, thereby giving deflection to the respective electron beams R, G and B by using this magnetic field.
Meanwhile, in this type of deflecting yoke apparatus, if a vertical direction in a screen is determined as a Y axis, there are generated a Y axis (vertical) horizontal misconvergence YH (Horizontal) that the electron beams R and B produce a displacement in a lateral direction with the Y axis therebetween and a Y axis (vertical) vertical misconvergence VCR (Vertical Convergence Ratio) that the electron beams G produce a displacement with respect to the electron beams R and B.
Therefore, in general, a frame coil is provided to the deflecting yoke apparatus in order to correct the displacement of the three types of electron beams R, G and B on the fluorescent screen. As this frame coil, there are a YH coil used to correct the Y axis horizontal misconvergence YH and a VCR coil used to correct the Y axis vertical misconvergence VCR.
However, it is actually difficult to correct the Y axis horizontal misconvergence YH to a practically sufficient level due to a collapse of a waveform of current provoked when a reverse current is led to the YH coil in a vertical blanking period. As a result, there is generated a problem that an image quality is deteriorated.
Each of Jpn. Pat. Appln. KOKAI No. 11-167884, Jpn. Pat. Appln. KOKAI No. 7-193831, Jpn. Pat. Appln. KOKAI No. 2001-101983 and Jpn. Pat. Appln. KOKAI No. 2000-41264 discloses a structure to correct the Y axis horizontal misconvergence YH. However, these laid-open publications do not have a description about dealing with a deterioration in an image quality caused when a reverse current is led to the YH coil used to correct the Y axis horizontal misconvergence YH in the vertical blanking period at all.
According to one aspect of the present invention, there is provided a deflecting yoke apparatus comprising: first and second frame coils configured to correct a vertical horizontal misconvergence in a screen; first and second main coils which are wound around a core and configured to deflect in a vertical direction electron beams which have passed through a magnetic field generated by the first and second frame coils; first and second sub-coils which are wound around the core and configured to deflect in the vertical direction the electron beams which have passed through the magnetic field generated by the first and second frame coils; a first deflecting current supply portion configured to pass a serriform deflecting current to the first and second main coils; and a second deflecting current supply portion configured to supply to the first and second sub-coils through a first and second diodes connected in parallel so as to have opposed directions a deflecting current which is supplied to the first and second main coils by the first deflecting current supply portion.
According to another aspect of the present invention, there is provided a television receiver comprising: a reception portion configured to receive a television broadcast signal; a signal processing portion configured to generate a video signal from the television broadcast signal received by the reception portion; a deflecting current generation portion configured to generate a deflecting current from the television broadcast signal received by the reception portion; a deflecting yoke portion configured to generate a magnetic field which deflects electron beams by using the deflecting current generated by the deflecting current generation portion; and a display portion configured to display the video signal generated by the signal processing portion as a screen image by deflecting the electron beams by using the magnetic field generated by the deflecting yoke portion, the deflecting yoke portion comprising: first and second frame coils configured to correct a vertical horizontal misconvergence in the screen; first and second main coils which are wound around a core and configured to defect in the vertical direction electron beams which have passed through a magnetic field generated by the first and second frame coils; first and second sub-coils which are wound around the core and configured to deflect in the vertical direction the electron beams which have passed through the magnetic field generated by the first and second frame coils; a first deflecting current supply portion configured to pass a serriform deflecting current to the first and second main coils; and a second deflecting current supply portion configured to supply to the first and second sub-coils through first and second diodes connected in parallel so as to have opposed directions a deflecting current which is supplied to the first and second main coils by the first deflecting current supply portion.